//实现类:Projector.java
public class Projector implements Device {
    private String brand; //品牌

    public Projector(String brand) {
        this.brand = brand;
    }

    //必须实现接口的所有方法
    public void powerOn() {
        System.out.print(brand + "投影仪开机，正准备预热...");
    }

    public void powerOff() {
        System.out.println(brand + "投影仪关机，散热中...");
    }

    @Override
    public void repair() {

    }
}






    